Various portable devices, such as laptop computers, personal digital assistants (PDA's), portable digital and video cameras, portable music players, portable electronic games, and cellular phones or other wireless devices, require portable power sources. The weight and inconveniences of single-use batteries and rechargeable batteries have motivated efforts to replace those power sources for portable use. Thus, there is an increasing demand for light-weight, re-usable, efficient, and reliable power sources in such applications and in many other applications as well. In attempts to meet these needs, various portable fuel cells have been developed, such as ceramic-based solid-oxide fuel cells, direct methanol fuel-cell (DMFC) systems, reformed-methanol-to-hydrogen fuel-cell (RMHFC) systems, and other proton-exchange-membrane (PEM) fuel-cell systems. For those fuel cells that use a gas such as hydrogen as their fuel, local generation of the gas is desirable, and may be significantly safer than storing a quantity of gas. Heating of a source substance to evolve gas for the fuel cell's fuel can be an efficient way to generate the gas locally. The efficiency of such an arrangement depends upon minimizing heat loss. There is a continuing need and a large anticipated market for improved practical compact portable fuel cells with rapid startup times and improved efficiency.